Obama on Syria: 'I have not made a decision'

8/28/13 6:07 PM EDT

President Obama said Wednesday he is still deciding how to respond to the use of chemical weapons in Syria.

"I have not made a decision," he told the "PBS News Hour” in his most extensive comments since the Aug. 21 attack in the outskirts of Damascus.

His comments came as the White House prepares to brief members of Congress on Thursday afternoon about developments in Syria, possibly laying the groundwork for a targeted attack against Bashar al-Assad's regime. As growing number of lawmakers from both parties are calling on Obama to detail the intelligence and rationale behind a strike, the president made the case Wednesday that the United States must protect its "core self-interest" and respond to the use of chemical weapons.

"I think it's important that if, we make a choice to have repercussions for the use of chemical weapons, then the Assad regime, which is involved in a civil war, trying to protect itself, will have received a pretty strong signal, that in fact, it better not do it again," Obama said.

While that "doesn’t solve all the problems inside of Syria, and, you know, it doesn’t, obviously end the death of innocent civilians inside of Syria," it would be a necessary response to the large-scale use of chemical weapons against civilians, he said.

"When you start talking about chemical weapons in a country that has the largest stockpile of chemical weapons in the world, where over time, their control over chemical weapons may erode, where they’re allied to known terrorist organizations that, in the past, have targeted the United States, then there is a prospect, a possibility, in which chemical weapons that can have devastating effects could be directed at us," he said. "And we want to make sure that that does not happen."

Administration officials have made clear that Obama isn't angling for "regime change" with any intervention, a point he touched upon as he stressed that the goals of the United States and its allies are less dramatic. He's considering "limited, tailored approaches, not getting drawn into a long conflict, not a repetition of, you know, Iraq, which I know a lot of people are worried about," he said.

What he's hoping for, he added, is to, in "a clear and decisive but very limited way ... send a shot across the bow saying, stop doing this, that can have a positive impact on our national security over the long term."

Eventually, though, he still hopes for a political transition in Syria and is "prepared to work with anybody -- the Russians and others" to help make that happen.

Among the members of Congress asking Obama for more information on Syria is House Speaker John Boehner (R-Ohio), who sent a list of 14 questions to the president on Wednesday afternoon. “It will take presidential leadership and a clear explanation of our policy, our interests, and our objectives to gain public and congressional support for any military action against Syria,” Boehner said. “After spending the last 12 years fighting those who seek to harm our fellow citizens, our interests, and our allies, we all have a greater appreciation of what it means for our country to enter into conflict. It will take that public support and congressional will to sustain the administration’s efforts, and our military, as well as their families, deserve to have the confidence that we collectively have their backs — and a thorough strategy in place.”

A dozen Democrats, led by Rep. Barbara Lee (D-Calif.), have signed a letter asking Obama to “seek an affirmative decision of Congress prior to committing any U.S. military engagement to this complex crisis." If Obama doesn't have congressional support, Rep. Jim McDermott (D-Wash.) told POLITICO on Wednesday, “you’ll see a lot of people saying this is an absolute mistake, they should not have done it, I do not support it. The storm will follow if [Obama] goes without having the backing of the Congress.”